Add a --startup option to generate combined traces for startup.

tools/profile_chrome/main.py

Index: tools/profile_chrome/main.py
diff --git a/tools/profile_chrome/main.py b/tools/profile_chrome/main.py
index 1dbf08a60d9e98cf67ca6f21cebc369988aaf689..2a7af95dd7c95674818bf0825052c852185ada59 100755
--- a/tools/profile_chrome/main.py
+++ b/tools/profile_chrome/main.py
@@ -74,6 +74,12 @@ def _CreateOptionParser():
                                  'profiling-tool for detailed instructions for '
                                  'profiling.')
 
+  parser.add_option('--startup', help='Trace Chrome Startup. Possible values '
+                    'are "warm" and "cold". The "warm" start does not perform '
+                    'special steps, while the "cols" flushes the OS page cache '
+                    'before start. Note that "cold" requires a device with root'
+                    ' access.', default=None, choices=['warm', 'cold'])
+
   timed_options = optparse.OptionGroup(parser, 'Timed tracing')
   timed_options.add_option('-t', '--time', help='Profile for N seconds and '
                           'download the resulting trace.', metavar='N',
@@ -210,8 +216,9 @@ When in doubt, just try out --trace-frame-viewer.
         perf_controller.PerfProfilerController.GetCategories(device)))
     return 0
 
-  if not options.time and not options.continuous:
-    ui.PrintMessage('Time interval or continuous tracing should be specified.')
+  if not options.time and not options.continuous and not options.startup:
+    ui.PrintMessage('Time interval, continuous or startup tracing should be '
+                    'specified.')
     return 1
 
   chrome_categories = _ComputeChromeCategories(options)
@@ -223,19 +230,22 @@ When in doubt, just try out --trace-frame-viewer.
                     'Chrome tracing results in duplicate trace events.')
 
   enabled_controllers = []
-  if chrome_categories:
-    enabled_controllers.append(
-        chrome_controller.ChromeTracingController(device,
-                                                  package_info,
-                                                  chrome_categories,
-                                                  options.ring_buffer,
-                                                  options.trace_memory))
+  # Enable the systrace and chrome controller. The systrace controller should go
+  # first because it provides early events used in the chrome controller.
   if systrace_categories:
     enabled_controllers.append(
         systrace_controller.SystraceController(device,
                                                systrace_categories,
                                                options.ring_buffer))
 
+  if chrome_categories:
+    enabled_controllers.append(
+        chrome_controller.ChromeTracingController(device,
+                                                  package_info,
+                                                  chrome_categories,
+                                                  options.ring_buffer,
+                                                  options.trace_memory,
+                                                  options.startup))
   if perf_categories:
     enabled_controllers.append(
         perf_controller.PerfProfilerController(device,
@@ -249,7 +259,7 @@ When in doubt, just try out --trace-frame-viewer.
     options.output = os.path.expanduser(options.output)
   result = profiler.CaptureProfile(
       enabled_controllers,
-      options.time if not options.continuous else 0,
+      options.time if options.time else 0,
       output=options.output,
       compress=options.compress,
       write_json=options.json)